At present, in an image display apparatus such as a Liquid Crystal Display (LCD) and an Organic Light Emitting Diode (OLED), a pixel unit is composed of a red (R) sub-pixel unit, a green (G) sub-pixel unit, and a blue (B) sub-pixel unit, and color desired to be displayed is obtained by mixing through controlling a gray-scale value of each sub-pixel unit so as to display a color image. Since luminous efficiency of three primary colors RGB is low, product optimization of a display device based on the three primary colors RGB will be restricted. On such basis, a pixel unit composed of the red (R) sub-pixel unit, the green (G) sub-pixel unit, the blue (B) sub-pixel unit and a white (W) sub-pixel unit appears, to improve the luminous efficiency of the RGB display. However, signal transmission interfaces, such as a Video Graphics Array (VGA) interface and a Digital Video Interface (DVI), all transmit an RGB signal. If the RGB signal is directly applied to an RGBW display, image distortion will be caused. Therefore, it is necessary to convert the RGB signals inputted to the RGBW display.
The four types of sub-pixel units in each frame of display have different working strengths and working time, so that working lives of the four types of sub-pixel units are not uniform, wherein the working life of the sub-pixel unit with the shortest working life represents a service life of the entire display. In a conventional image conversion method for converting RGB signal to RGBW signal, although the working lives of the three types of sub-pixel units, i.e., the red (R) sub-pixel unit, the green (G) sub-pixel unit and the blue (B) sub-pixel unit can be improved by adding the white (W) sub-pixel unit, since the working lives of the four types of sub-pixel units are not uniform, the service life of the entire display cannot be effectively improved.
Therefore, how to effectively improve the service life of the entire display is a technical problem urgent to be solved by those skilled in the art.